Field
The disclosed concept relates generally to electrical switching apparatus and, more particularly, to circuit interrupters, such as, for example, circuit breakers. The disclosed concept also relates to jumpers for electrical switching apparatus. The disclosed concept further relates to methods of making jumpers.
Background Information
Circuit breakers are typically available in one-, two-, three- and four-pole construction, although larger counts of poles are possible. It is known to connect multiple poles of circuit breakers in series to provide a high voltage for a low voltage switching and interruption device (e.g., without limitation, 750 VDC; 1000 VDC; 1500 VAC). For a 1000 VDC application, for example, typically multiple circuit breakers are electrically tied together. Most known existing six-pole or eight-pole air circuit breakers are designed such that the poles are electrically connected internally in breaker structures in a predetermined manner.
It is known that to obtain higher interruption and voltage ratings, circuit breaker poles can be wired in series. Normally, cable or bus bars are electrically connected to the circuit breaker terminals, which carry the current and remove a significant amount of the heat that is generated within the breaker. A conventional shorting strap, commonly referred to as a jumper, electrically connected between poles can carry the current, but does not remove much heat, resulting in relatively high temperature rises at the circuit breaker terminals. Commonly assigned United States Patent Application Publication No. 2013/0213780 discloses an example jumper for electrically connecting electrical switching apparatus poles.
Consumer markets demand a circuit breaker jumper that both occupies relatively little space and operates at relatively low temperatures. The conventional tradeoff in jumper design, however, is between size and thermal performance (e.g., heat transfer). That is, to achieve lower operating temperatures, typically the size of the jumper must increase, and vice versa. Stated another way, jumper designs must generally concede in one of these areas, or otherwise be cost-prohibitive.
There is room, therefore, for improvement in electrical switching apparatus, such as circuit breakers, and in jumpers and associated methods therefor.